The present invention relates to cutting inserts for chipforming machining of preferably metallic work places.
Such cutting inserts are normally provided with one or more cutting edges formed by the transition between the top surfaces or rake faces of the insert and its side surfaces or clearance faces.
In cutting operations, the breaking of the chip and the shape of the chip are often of great importance for an undisturbed production. In modern, high-productive machines or tools there are great demands upon an efficient removal of the chips. Long and uncontrolled chips can easily cause breakdowns and rejections and they also mean great risks for accidents. The chip control has therefore to be carefully regarded and it determines the design of the tools to a great extent.
It is known that different effects regarding chip breaking and chip removal can be obtained by means of different kinds of depressions in the rake face of a cutting tool. As an example, by supplying the rake face of the cutting tool with notches or grooves extending essentially in the direction of motion of the chip, a partition or longitudinal breakage of the chip has been obtained leading to an easier removal of the chip. In other cases, a special plastic deformation of the chip has been reached by shaping the depression or grooves in a somewhat different way, meaning that the chip has obtained a stiffened bead or bend. This phenomenon has in its turn caused effects of a favorable nature regarding the chip removal such as, for example, a decrease of the width or a decreased radius of curvature of the chip.
It is also known to provide the rake face with depressions not intended to cause any breaking or plastic deformation of the chip, altogether. On the other hand, it is also known to use depressions or chip breaker grooves which cause various kinds of chip upsetting, breaking or plastic deformation acting separately or in combination depending upon the actual cutting conditions.
Thus, by special shaping of the grooves or the depressions applied on the rake faces of cutting inserts, completely new and unexpected effects can be reached.
It is, therefore, an object of the present invention to provide a novel cutting insert.
It is another object of the invention to provide a cutting insert which requires less cutting forces.
It is a further object of the invention to provide a cutting insert which performs satisfactorily within a wide range of cutting speeds.
It is yet another object of the invention to provide a cutting insert which facilitates guidance of a drill where separate guide pads are omitted.
It is still another object of the invention to provide a cutting insert which increases the plastic deformation or stiffening of the chips.